Process for preparing ester lactones



Patented Oct. 11, 1949 LACTON Hugh J. Hagcmeyer, Jr., Kingsport, Tenn., as signor to Eastman Kodak Company, Rochester, N. Y,., a corporation .of New Jersey NoDrawing. Original application May 15, 1946, Serial N0. 670,032. Divided and this application September 10, 1947, Serial No. 773,294

1 Claim. 1

This invention relates to the preparation of carboxylic acids and more particularly to the preparation of substituted aliphatic carboxylic acids by the reductionoi ,s-lactones obtained from aromatic aldehydes, or aromatic ketones, and polymers of such fi-lactones.

This is a division of my copending patent application entitled Preparation of aliphatic-carboxylic acids, Serial No. 670,032, filed May 15, 1946.

The p-lactones employed as starting materials in my invention may be prepared by condensing a ketene with an aromatic aldehyde or an aromatic ketene in the presence :of a suitable catalyst, such as a Friedel-Crafts type catalyst, or in the presence of sodium, potassium or lithiumsalts of organic carboxylic acids, for example, sodium acetate at temperatures below 50 "C. The use of a Friedel-Crafts catalyst in forming pelactones is described in U. S. Patent 2,356,459 of August 22, 1944; and the reaction of ketene with furfural and benzaldehyde in the presence of potassium acetate as the catalyst is described by C. D.'Hurd, J. A. C. S. 55, 275 (1933). The reaction for preparing these B-lactones can :be represented by the equation wherein n is any whole number 1,2, 3, 4, etc.; R may be hydrogen, alkyl, e. g. methyl or ethyl, and aryl, e. g. phenyl; and R may be aryl, e. g. phenyl or naphthyl, and cycloalkyl, e. g. cyclohexyl or a heterocyclic group, e. g. furyl.

Polymerization of these lactonestcan be carried out as described in U. S. Patent 2,361,036 of August 22, 1944.

An object of the invention is to provide a method of preparing organic carboxylic acids of the general formula wherein n represents a whole number 1, 2, 3, 4, etc.; R may be aromatic, e. g. phenyl or naphthyl, and cycloaliphatic, e. g. cyclohexyl, or furyl; and R and B" may be hydrogen, methyl, ethyl, phenyl, etc.

Another object of the invention is to provide a method for the hydrogenation of fi-lactones made from aromatic aldehydes and aromatic ketones, and low molecular polymers of such B- lactones, to carboxylic acids.

Still another object is to prepare ester lactones by the hydrogenation of the addition products of ketenes with furfural, said ester-lactones having the iollowing general structure:

wherein R may be hydrogen, methyl, ethyl, phenyl, etc.

Other objects will become apparent hereinafter. In accordance with the invention, it has been discovered that substituted, aliphatic carboxylic acids can be prepared by the hydrogenation of the fl-lactones obtained from aromatic aldehydes and aromatic ketones, and also by hydrogenation of catalyst R (CHa),.-1CHRORR"COOH Carboxylic acid In this equation, R, R, R" and n have the significance described above.

The. invention will be .further understood by reference to the following examples.

Example I Ketene was passed in through a high speed stirrer into grams of benzaldehyde containing 0.5 gram of anhydrous sodium acetate while maintaining a react-ion temperature of 30-40 C. The p-phenyl-fl-propiono lactone thus produced was then placed in a stirrer type copper lined autoclave and hydrogenated using Raney nickel 3 catalyst at 180 C. and 700 pounds per square inch until no more hydrogen was absorbed. Distillation gave 84 grams of fi-cyclohexyl propionic acid. B. P.10 141 C. N13 1.4624, N. E. 155. The reaction may be expressed by the following equation:

C5H5CHO CHa=C=O v Benz- Ketene aldehyde 7 OBHBCHO H, CBHHOHZOHZCOOH GHQ-0:0 fl-Cyclqhexyl propiomc acid B-PhenyI'betapropiono lactone Example II fi-Phenyl-B-butyro lactone Acetophenone CtHnCH (CH3) CHzCO OH fl-Cyclohexyl butyric acid Example III 250 grams of furfural containing 0.5 gram of anhydrous potassium acetate was treated with ketene while maintaining a reaction temperature of 30 to 40 0., thereby forming ,8- (2-furyl) fi-propiono lactone. When an increase in weight of 100 grams had been obtained, the reaction mixture was diluted with 400 grams of dio'xane and reduced to the acid at 165 C. over Raney nickel. Distillation gave 140 grams of B- (Z-tetrahydro-furyl) propionic acid. B. P. 126 C. N. E. 128. The reaction is as follows:

Furfural Ketene (IJHF C: O

B-(Z-furyD-fl-propiono lactone As indicated in the above examples, the simple lactones may be hydrogenated as such, or in accordance with another feature of the invention, they may be partially polymerized to the polyesters of B-hydroxy acids and then reduced to substituted acids. Polymerization is carried out as described in U. S. Patent 2,361,036. 8- lactones have a tendency to form a dimer which has a greater heat stability than the simple lactone. The dimer and higher polymers have the advantage over the simple lactone in that the reduction takes place readily at lower temperatures and pressures. This fact permits the preparation of aryl substituted aliphatic acids in accordance with my invention as shown in the following example.

Emample IV 200 grams of benzaldehyde containing 0.2 gram of ZIICIZ were reacted with ketene at 0-10 C. The catalyst was washed out with 5% alkali. One gram of K2003 was added and the fi-phenylfl-propiono lactone was heated at C. for one hour under which conditions a low molecular weight polymer of this lactone was formed. The polymer mixture was placed in a small stirrer type autoclave and reduced over Raney nickel at to C. Distillation of the product gave 102 grams of B-phenyI propionic acid, B. P.10 C. Crystals were obtained upon cooling. M. P. 46 to 48 C. The following equation represents the reaction in which x indicates the extent of polymerization and may be a whole number:

lit-0:0 In accordance with another feature of the invention, ester-lactones may be prepared by the hydrogenation of the addition products of ketenes with furfural. These ester-lactones are valuable plasticizers for molding materials made from cellulose esters.

Example V Ketene was passed into 300 grams of furfural containing 0.5 gram anhydrous potassium acetate until the theoretical increase in weight had taken place, thus indicating the formation of the acid as illustrated in the following equation:

CH-CH n in; t 6 4 +CH-.\ C- O OH o 0 o --o This c-lactone was diluted with 400 grams of dioxane and placed in a stirrer type autoclave with 5 grams of Raney nickel and reduced with hydrogen. 'The reduction was conducted in two stages of temperature. The first reduction was conducted at atemperature of C. for 4 hours and the ii-lactone was reduced to ,3-(2- tetrahydrofuryl) -propionic acid which was then further reduced at a temperature of 210 C. to produce zeta hydroxy-gamma-heptolactone as shown in the equation.

with the fl-(2-tetrahydrofuryl) -propionic acid to yield an ester-lactone as shown in the equation.

This example presents a new method for forming this ester-lactone which is described and claimed in Hasche and Gordon Patent 2,364,358 of December 5. 1944.

These examples illustrate preferred conditions for making substituted aliphatic carboxylic acids by the reduction of the B-lactones obtained from aromatic aldehydes and aromatic ketones, and polymers of such S-lactones. It will be understood that a relatively large number of such acids can be produced in a like manner from comparable lactones and ester-lactones. In general, the reaction can be carried out at a temperature between -240" C. although the preferred ranges are: for simple lactones, -190 C.; for dimers and/or polymers, 90-190 C.; and ester lactones, 210-230 C. Pressures up to atmospheres are desirable. Higher pressures may be used, but there appears no substantial advantage in employing such higher pressures. The hydrogenation may be carried out in the presence of inert diluents such as dioxane, cyclohexane, and heptane.

With lactones containing furfural and derivatives thereof a diluent is preferably employed to aid in controlling the rate of the reaction.

The Raney nickel catalyst employed in the reduction of the B-lactones described herein may be prepared as shown in U. S. Patents 1,628,190 and 1,915,473 by a method of leaching out aluminum from a nickel-aluminum alloy with sodium 6 hydroxide. While Raney nickel is the preferred catalyst, other suitable hydrogenation catalysts may be used such as nickel on kieselghur.

I claim:

The process for preparing an ester-lactone comprising hydrogenating in a closed vessel at super atmospheric pressures and in the presence of a hydrogenating catalyst the fi-lactone of 18- (2-fury1) -fl-hydroxy propionic acid, the hydrogenation being conducted first at a temperature of approximately C. and continued thereafter for approximately four hours at 210 C.

HUGH J. HAGEMEYER, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,364,358 Hasche et a1 Dec. 5, 1944 2,397,629 Snyder Apr. 2, 1946 OTHER REFERENCES Boese, et al., Industrial 8,: Engineering Chemistry, Jan. 1940, pages 16 to 22. 

